No, that doesn't solve the problem -- I had a few megabytes of fast RAM, and it still sucked. The chipset bus is completely contended in 4 bitplane high res gr

No, that doesn't solve the problem -- I had a few megabytes of fast RAM, and it still sucked. The chipset bus is completely contended in 4 bitplane high res graphics in OCS/ECS, so any attempt to access the serial port registers is blocked until the horizontal blanking interval (as is chip or slow RAM). The faster and wider data path in the AGA chipset improved this substantially, but that data path was only used for video DMA, not for the blitter or other chipset register accesses. The only real solution was to use an aftermarket serial port card that wasn't on the chipset bus and used a real UART like the 16550 that had a 16 byte FIFO.